Recent work has demonstrated that certain chemicals and medications used in Ophthalmology are capable of altering the physiologic function and anatomical appearance of the corneal endothelium. The purpose of this investigation is to define physiological and ultrastructural changes produced in the corneal endothelium by drugs, chemicals and pathological conditions. Instrumentation used will include the specular microscope, flux chambers, and electron microscope. Compounds and conditions to be studied include free radicals, peroxides, ocular inflammation, corticosteroids, corneal preservation and bicarbonate flux.